title: A case-control study of occupational exposure to trichloroethylene and non-Hodgkin lymphoma.
abstract: BACKGROUND
  Previous epidemiologic findings suggest an association between exposure to trichloroethylene (TCE), a chlorinated solvent primarily used for vapor degreasing of metal parts, and non-Hodgkin lymphoma (NHL).
  
  
  OBJECTIVE
  We investigated the association between occupational TCE exposure and NHL within a population-based case-control study using detailed exposure assessment methods.
  
  
  METHODS
  Cases (n = 1,189; 76% participation rate) and controls (n = 982; 52% participation rate) provided information on their occupational histories and, for selected occupations, on possible workplace exposure to TCE using job-specific interview modules. An industrial hygienist assessed potential TCE exposure based on this information and a review of the TCE industrial hygiene literature. We computed odds ratios (ORs) and 95% confidence intervals (CIs) relating NHL and different metrics of estimated TCE exposure, categorized using tertiles among exposed controls, with unexposed subjects as the reference group.
  
  
  RESULTS
  We observed associations with NHL for the highest tertiles of estimated average weekly exposure (23 exposed cases; OR = 2.5; 95% CI, 1.1–6.1) and cumulative exposure (24 exposed cases; OR = 2.3; 95% CI, 1.0-5.0) to TCE. Tests for trend with these metrics surpassed or approached statistical significance (p-value for trend = 0.02 and 0.08, respectively); however, we did not observe dose–response relationships across the exposure levels. Overall, neither duration nor intensity of exposure was associated with NHL, although we observed an association with the lowest tertile of exposure duration (OR = 2.1; 95% CI, 1.0-4.7).
  
  
  CONCLUSIONS
  Our findings offer additional support for an association between high levels of exposure to TCE and increased risk of NHL. However, we cannot rule out the possibility of confounding from other chlorinated solvents used for vapor degreasing and note that our exposure assessment methods have not been validated.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland 20892, USA. purduem@mail.nih.gov
authors.forename: Mark P
authors.initials: MP
authors.lastname: Purdue
authors.forename: Berit
authors.initials: B
authors.lastname: Bakke
authors.forename: Patricia
authors.initials: P
authors.lastname: Stewart
authors.forename: Anneclaire J
authors.initials: AJ
authors.lastname: De Roos
authors.forename: Maryjean
authors.initials: M
authors.lastname: Schenk
authors.forename: Charles F
authors.initials: CF
authors.lastname: Lynch
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Lindsay M
authors.initials: LM
authors.lastname: Morton
authors.forename: James R
authors.initials: JR
authors.lastname: Cerhan
authors.forename: Richard K
authors.initials: RK
authors.lastname: Severson
authors.forename: Wendy
authors.initials: W
authors.lastname: Cozen
authors.forename: Scott
authors.initials: S
authors.lastname: Davis
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Rothman
authors.forename: Patricia
authors.initials: P
authors.lastname: Hartge
authors.forename: Joanne S
authors.initials: JS
authors.lastname: Colt
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000139:chemically induced / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D014241:Trichloroethylene / Q000633:toxicity*
chemical_list: D014241:Trichloroethylene